Research in Engineering Education Symposium 2011 - rees2009

Universidad Politécnica de Madrid (UPM) Página 109 de 957
sent to student electronically. However, unless the student requests it, images generated
by the commercial scanner of figure 1 will be sent be sent to him.
Figure 2: Ellipse adjustment by orthogonal regression (units in µm)
Instrument adjustment
Automatic edge detection routines work with black and white images of the measurand.
The scanner can directly provide black and white images or, when neccesary, generate
grayscale or color images that will be manually adjusted (contrast, brightness, saturation,
etc ...) and converted to black and white using standard photo editing software (see figures
3a and 3b). Unless student shows a particular interest in working with color or grayscale
images LMM will send him only black and white images.
In any case, edge detection routines work with an array of zeros (dark) and ones (light) in
which pixel position is known through the indices i and j of the pixel in the array. The
subscript i grows when moving down along the image and the subscript j grows when
moving right.
Proceedings of Research in Engineering Education Symposium 2011
Madrid, 4 th - 7 th October 2011